The claimed invention relates generally to disc drive data storage devices and more particularly to a latch for the disc drive.
Data storage devices of the type known as xe2x80x9cWinchesterxe2x80x9d disc drives are well known in the industry. These disc drives magnetically record digital data on several circular, concentric data tracks on the surfaces of one or more rigid discs. The discs are typically mounted for rotation on the hub of a spindle motor. In disc drives of the current generation, the discs are rotated at speeds of 10,000 revolutions per minute or more.
Data are recorded to and retrieved from the discs by an array of vertically aligned read/write head assemblies, or heads, which are controllably positioned by an actuator assembly. Each head typically includes electromagnetic transducer read and write elements which are carried on an air bearing slider. The slider acts in a cooperative hydrodynamic relationship with a thin layer of air dragged along by the spinning discs to fly each head in a closely spaced relationship to the disc surface. In order to maintain the proper flying relationship between the heads and the discs, the heads are attached to and supported by head suspensions or flexures.
Historically, the actuator assembly used to position the heads has assumed many forms. Most disc drives of the current generation incorporate an actuator of the type referred to as a rotary voice coil actuator. A typical rotary voice coil actuator includes a pivot shaft fixed to a disc drive housing base deck at a location adjacent an outer edge of the discs. The pivot shaft is mounted such that its central axis is normal to the plane of rotation of the discs. An actuator bearing housing is mounted to the pivot shaft by an arrangement of precision ball bearing assemblies. The actuator bearing housing supports a coil that is immersed in a magnetic field of permanent magnets. The permanent magnets are mounted to the disc drive housing base deck.
On the side of the actuator bearing housing opposite the coil are a plurality of vertically aligned, radially extending actuator arms. The flexures are mounted to the actuator arms. When current is applied to the coil, the coil produces a magnetic field that interacts with the magnetic field of the permanent magnets to pivot the actuator bearing housing about the pivot shaft, thereby moving the heads across the disc surfaces.
Disc drives of the current generation are included in desk-top computer systems for office and home environments, as well as in laptop computers. Because of this wide range of operating environments, the computer systems, as well as the disc drives incorporated in them, must be capable of reliable operation over a wide range of ambient temperatures and mechanical forces.
When the disc drive is not in use, the read/write heads are brought to rest upon parked locations of the discs. These parked locations are regions on the discs separate from the data storage locations. Typically, each parked location provides a landing zone on each of the disc surfaces where the read/write heads are positioned before the rotational velocity of the spinning discs decreases below a threshold velocity necessary to sustain an air bearing. The parked location is typically located near an inner diameter of the discs.
After the heads are in the parked location, it is necessary to secure the actuator assembly by a latch to prevent the heads from subsequently moving onto the data locations of the discs while the disc drive is not in use. Latches are well known in the art and have included various configurations of springs, solenoids, and magnets to secure and release the actuator. For example, see U.S. Pat. No. 6,134,077 entitled LATCH FOR DISC DRIVES, issued Oct. 17, 2000 to Misso et al., U.S. Pat. No. 5,187,627 entitled MAGNETIC LATCH AND CRASH STOP, issued to Feb. 16, 1993 to Hickox et al., and U.S. Pat. No. 5,224,000 entitled CRASH STOP AND MAGNETIC LATCH FOR A VOICE COIL ACTUATOR, issued Jun. 29, 1993 to Casey et al. All of these patents listed above are assigned to the assignee of the present invention.
The actuator is moved to the latched and unlatched position many times over the operational life of a disc drive. The repetitive, typically high energy contacts between the actuator and the latch can lead to wear and particulation of the contact surfaces of the latch. Such particulates can be detrimental to the operation of the drive. As drives achieve ever higher levels of operational performance, it becomes increasingly important to provide latches with improved wear and non-particulating characteristics, and it is to such improvements that the present invention is directed.
In accordance with preferred embodiments, a latch is provided for use in a disc drive to secure an actuator assembly of the disc drive when the disc drive is not in use. The latch is made of a base polymer of polyetherimide (PEI) with additives of polytetrafluoroethylene (PTFE) and arimid fiber. The latch made from this material generates significantly fewer particles and provides substantially improved wear characteristics as compared to latches of the existing art. Also, a method is provided for making the latch.